Bismillah writes: Ross Anderson and Laurent Simon of Cambridge University studied a range of Android devices and found that even though a "factory reset" is supposed to fully wipe storage, it often doesn't. Interestingly enough, full-device encryption could be compromised by the incomplete wiping too. ITnews reports: "The researchers estimated that 500 million Android devices may not fully wipe device disk partitions. As many as 630 million phones may not wipe internal SD cards. Five 'critical failures' were outlined in the researchers' Security Analysis of Android Factory Resets paper.